This project comprises an investigation of polysaccharides of Astragalus varieties that will inhibit carcinogenesis. In phase I polysaccharides from five Astragalus varieties will be purified, identified, and screened for anticarcinogenicity. Fresh samples of the polysaccharides will be obtained from cultivars being grown on an expermiental farm in California. The polysaccharides will be identified by solution viscosity, acidity, optical rotation, stability, molecular size and infrared spectra. They will be tested for protective activity in two different systems. The first system comprises NIH-Swiss mice challenged with a retrovirus isolated from wild mice that leads to a splenic lymphoma. They will also be tested for protective activity against mammary tumor development in Sprague-Dawley rats adminsitered the chemical carcinogen N-methyl-N-nitrosourea. The two bioassays will be completed well within the 6 month term of this grant. Similar polysaccharides have been shown to protect mice against transplanted ascites tumors, probably by a biological response modifier mode of action. The project will begin to systematically define structure-activity relations in Astragalus polysaccharides as inhibitors of carcinogenesis. A goal is a plant derived non-toxic polysaccharide that will prevent the formation of tumors or aid in the treatment of cancer.